This is common among capture setups. Start recording several seconds before playing the tape. 150 frames is just 5 seconds, and while longer than most (2-3 seconds), it's not unreasonable. I'd only complain if it went out 10 seconds.
This is similar to the analog days, where you were supposed to start recording tape (lead-in) before you wanted to start recording.
I have a system that gives quick audio "pop" when the capture starts, but you never hear it on my captures because that was discarded before the final file (scrubbed, proofed) was created. Captures are rough, and should always be scrubbed/proofed, then re-output as Direct Stream Copy (assuming AVI using
VirtualDub). Anything bad before/after, even during, is simply cut and discarded, leaving you with the good capture file for archive/processing.
You Win10 could be many things, and is likely multiple issues at once. Unlikely it's a single problem. For starters, you can't capture on a system running anti-virus/malware, internet notifications, and other digital "noise" to distract the system from the complex task of capturing. And if Win10 is good at anything, it's noise.